1. Field of the Invention
The present invention relates to a sensor circuit module and an electronic device including such a sensor circuit and, more particularly, to a sensor circuit module such as a vibration gyro for use as a device for correcting video-camera shaking, and an electronic device including such a vibration gyro.
2. Description of the Related Art
FIG. 10 is an exploded perspective view of a vibration gyro which is a sensor circuit module of the related art. In FIG. 10, a vibration gyro 1 includes a packaging substrate 2, a vibrator 4 which is a sensor element mounted onto the packaging substrate, a chip type semiconductor element 5 mounted by flip-chip bonding, a chip element 6 such as a chip resistor or a chip capacitor, and a cover 7. The packaging substrate 2 is made of resin. Four through-hole terminals 3 are provided on end surfaces of the substrate 2, and are formed by splitting each through-hole, which is formed on the packaging substrate 2, substantially into two halves.
Of these components, the semiconductor element 5 contains an integrated circuit having a circuit for driving the vibrator 4 and a circuit for detecting a Colioris force based on a signal output from the vibrator 4. The integrated circuit includes an amplifier circuit having a high amplification factor, since the semiconductor element 5 processes fine signals. The through-hole terminals 3 are used for input and output of a signal and grounding.
FIG. 11 is a perspective view of the semiconductor element 5. In FIG. 11, the semiconductor element 5 includes a semiconductor substrate 5a, a circuit-formation area 5b located in the center of one main surface of the semiconductor substrate 5a, and a plurality of bumps 5c arranged so as to surround the circuit-formation area 5b on the one main surface of the semiconductor substrate 5a. 
FIG. 12 is a plan view showing a portion of the packaging substrate 2 onto which the semiconductor element 5 is mounted. As shown in FIG. 12, an area 2b of the packaging substrate 2 for mounting the semiconductor element 5 has a plurality of wiring electrodes 2a disposed thereon so as to correspond to a plurality of the bumps 5c of the semiconductor element 5. The semiconductor element 5 is flip-chip-mounted onto the area 2b of the packaging substrate 2 with the one main surface of the semiconductor element 5 being brought into contact with the area 2b. Thus, a plurality of the bumps 5c is connected to a plurality of the wiring electrodes 2a. 
No electrodes are located in a portion of the area 2b of the packaging substrate 2 for mounting the semiconductor element 5, the portion of the area 2b being opposed to the circuit-formation area 5b of the semiconductor element 5 to avoid generation of stray capacitance.
If an external light is irradiated onto the above-described vibration gyro 1, an output signal therefrom is varied. That is, problematically, the vibration gyro 1 malfunctions. This is caused as follows: when a light enters the packaging substrate 2 through an end surface thereof, the light passes through the inside of the packaging substrate 2, and reaches the circuit-formation area of the semiconductor element 5 mounted by flip-chip bonding, and the semiconductor element 5 absorbs the light to generate an electromotive force. Especially, in the case in which the vibration gyro is used in a video camera, a flash and a remote controller, which are provided for the video camera, and infrared rays applied in infrared-ray communication exert influences so that the vibration gyro often malfunctions. In other words, when a semiconductor, which is not a chip type but is provided with terminals and resin-molded, is used, the above-described problems do not occur.
A light applied from the upper side of the packaging substrate 2 is shielded by the cover 7, while a light from the lower side of the packaging substrate 2 is shielded by an electrode formed on the back-surface of the packaging substrate 2 and an electrode formed on the surface of a printed substrate having the packaging substrate 2 mounted thereon, the electrode being positioned in contact with the back surface of the packaging substrate 2. Accordingly, such lights exert less influence over the semiconductor element 5.
The above-described problems are readily caused when a chip type semiconductor element is mounted by flip-chip bonding. Moreover, when the semiconductor element is mounted with the circuit-formation area thereof being arranged to face upward, and a wiring is formed by wire-bonding, similar problems also occur, due to a light which enters the packaging substrate through an end surface thereof, exits from the surface thereof, and reflects inside the cover.
In order to overcome the problems described above, preferred embodiments of the present invention provide a sensor circuit module which is prevented from malfunctioning due to an external light entering a packaging substrate via an end surface thereof, and an electronic device including such a sensor circuit module.
According to a preferred embodiment of the present invention, a sensor circuit module includes a packaging substrate, a sensor element mounted onto the packaging substrate, and a chip type semi-conductor element, the packaging substrate being provided with a light-transmission-stopping member arranged to prevent a light from being transmitted to a circuit-formation area of the semiconductor element through an end surface of the packaging substrate.
Preferably, the sensor circuit module further includes a cover for protecting the sensor element and the semiconductor element, the cover being mounted onto the packaging substrate so as not to cover the end surfaces of the packaging substrate.
Also, preferably, the semiconductor element includes an amplifier circuit having a high amplification factor.
Preferably, the light-transmission-stopping member is a light-shielding coating material coated onto the end surfaces of the packaging substrate.
Also, preferably, the end surfaces of the packaging substrate are substantially occupied by through-hole terminals for input and output of a signal and through-hole terminals for light-shielding.
Preferably, as the light-transmission-stopping member, a material constituting the packaging substrate has a low optical transmittance.
Preferably, the material constituting the packaging substrate preferably has an optical transmittance in the wavelength range of about 600 nm to about 1000 nm substantially equal to that in the wavelength range of about 400 nm to about 600 nm.
Preferably, the semiconductor element is mounted by flip-chip bonding, and as the light-transmission-stopping member, an electrode for light-shielding is disposed on the portion of the packaging substrate which is opposed to the circuit-formation area of the semiconductor element.
Preferably, the semiconductor element is mounted by flip-chip bonding, and as the light-transmission-stopping member, a resin having a light-shielding property is filled into a gap between the packaging substrate and the semiconductor element.
According to another preferred embodiment of the present invention, an electronic device includes one of the above-described sensor circuit modules.
The sensor circuit module of preferred embodiments of the present invention, having the above-described configuration, is advantageous in that the module is prevented from malfunctioning due to an external light entering the packaging substrate via an end surface thereof.
The electronic device of other preferred embodiments of the present invention is advantageous in that the performance of the device is greatly improved.
Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments with reference to the attached drawings.